Catherine Bloom's childhood fractured at age four when her parents died in an Earth rebellion, severing her from her two-year-old brother Triton. Adopted by a traveling circus, she mastered acrobatics and knife throwing. Years later, she secured Trowa Barton's place in the circus, forming a fiercely protective, sisterly bond without recognizing him as her biological sibling. Her lifelong hatred of war, forged in childhood loss, compelled her to aid Trowa's allies during conflict—sheltering Wufei Chang and healing Heero Yuy after his self-inflicted injuries. When amnesia struck Trowa, she falsely declared them siblings to deter his return to combat, though he later rejoined the war. After Endless Waltz, she confirmed Trowa was Triton, reclaiming her lost brother. By the Frozen Teardrop era (MC0021), Catherine discarded pacifism for warfare. She drilled an unnamed Trowa-lookalike boy in mobile suit piloting, circus arts, and environmental survival, frequently unleashing a volatile temper during his discipline. Her metamorphosis from performer to militarized instructor hinted at trauma from an undisclosed source.